Mary Feng, M.D.
Mary Feng, M.D. is a Radiation Oncology Physician in San Francisco, CA, registered under NPI 1720106693. This provider registers 2 separate taxonomy codes, which usually means they practise across more than one recognised specialty.
Getting there
The practice address on file is 1825 4TH STREET, L1101, San Francisco, CA 94143. We have not yet mapped what surrounds this office — parking, transit, and nearby pharmacies are added as our data collection reaches each location.
Credentials and Medicare
| Licence | State | Specialty |
|---|---|---|
| C143118 | CA | Radiation Oncology Physician primary |
| 4301079982 | MI | Radiation Oncology Physician |
| 4301079982 | MI | Student in an Organized Health Care… |
Licences are recorded in 2 states: CA, MI. Providers licensed in several states often practise near a state border or deliver telehealth across state lines.
- Status
- Approved
- Provider type
- Practitioner - Radiation Oncology
- PAC ID
- 2567554355
- Enrollment ID
- I20160819001417
Medicare enrolment is recorded as approved under the provider type Practitioner - Radiation Oncology. Being enrolled means the provider can bill Medicare; it does not tell you whether they are currently accepting new Medicare patients. Call the office to confirm.
Licensed in 2 states
This provider holds licences in 2 states: California and Michigan. The practice address on file is in San Francisco, CA, but a licence in another state usually means they see patients there too — either at a second location or by telehealth. If the address above is far from you, it is worth calling to ask whether they practise closer to where you live.
- Licence
- C143118
- Specialty
- Radiation Oncology Physician
Licence numbers are self-reported to NPPES at registration. They do not confirm a licence is currently active, in good standing, or valid for the specialty shown — only the state board can tell you that, which is why we link to each one.
What Radiation Oncology covers
A radiologist who deals with the therapeutic applications of radiant energy and its modifiers and the study and management of disease, especially malignant tumors. NUCC Health Care Provider Taxonomy, code 2085R0001X
All registered taxonomy codes
This provider registers 3 taxonomy codes. The primary code is what appears on most claims; the others record additional recognised specialties.
| Code | Specialty | Licence | State | |
|---|---|---|---|---|
| 2085R0001X | Radiation Oncology Physician Radiation Oncology | C143118 | CA | primary |
| 2085R0001X | Radiation Oncology Physician Radiation Oncology | 4301079982 | MI | |
| 390200000X | Student in an Organized Health Care Education/Training Program | 4301079982 | MI |
The taxonomy records how the provider classifies their own practice. It does not confirm which conditions they currently treat, whether they are accepting new patients, or which insurance they take — call the office for that.
Full NPPES record
An NPI-1 identifies a single person. It stays with the clinician for life, even if they move practice or change state, which is why the address on file can lag behind where they actually work today.
| NPI | 1720106693 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Mar 27, 2007 |
| Last updated | Sep 27, 2022 |
| Status | Active |
| Sole proprietor | No |
| Credential | M.D. |
| Practice address |
1825 4TH STREET, L1101 San Francisco, CA 94143 (415) 502-7222 |
| Mailing address |
1825 4TH STREET. M2260 BOX 4001 San Francisco, CA 94143 |
Number check
How the check works, step by step
Every NPI carries a Luhn check digit — the same scheme used on credit cards. CMS prefixes the number with 80840 before computing it, which marks it as a US health identifier.
| Digit | 8 | 0 | 8 | 4 | 0 | 1 | 7 | 2 | 0 | 1 | 0 | 6 | 6 | 9 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 7 | 4 | 0 | 2 | 0 | 3 | 6 | 9 |
Sum = 57 · next multiple of 10 = 60 · check digit = 3 · actual last digit = 3
A valid check digit only means the number is well-formed. It does not mean the provider is licensed, active, or in good standing — those are separate questions answered by the sections above.